Given a function of one-variable and a possible bracketing interval,
return the minimum of the function isolated to a fractional precision of
tol.

Parameters:

func : callable f(x,*args)

Objective function.

args

Additional arguments (if present).

brack : tuple

Triple (a,b,c) where (a<b<c) and func(b) <
func(a),func(c). If bracket consists of two numbers (a,c)
then they are assumed to be a starting interval for a
downhill bracket search (see bracket); it doesn’t always
mean that the obtained solution will satisfy a<=x<=c.